Surface diffusion of hydrogen on Si(111)7×7

The diffusion of atomic hydrogen on the Si(111)7×7 surface has been investigated experimentally by means of optical second-harmonic diffraction from a submonolayer grating of adsorbed hydrogen. With submicron grating periods, we are able to measure surface diffusivities D<10-14 cm2 s-1. We find a thermally activated diffusion process with a barrier of Ea=1.50.2 eV and a preexponential factor D0 of 10-3 cm2 s-1. © 1991 The American Physical Society.